Many process streams of vapors, such as effluents from chemical processing plants, refineries, etc., utilize combustors to destroy the gases or vapors prior to release to the atmosphere. However, with increasing demands on environmental control of emissions, the use of free flames to combust such effluents is in many cases unsatisfactory. A free flame also results, in some instances, in incomplete combustion and uncontrollable production of undesirable side products. The present process and apparatus provide a method for controlling and stabilizing the reaction wave, which is flameless, in which the gases are reacted within a controlled area of the matrix at substantially uniform and relatively low temperatures. The uniformity of the reaction wave provided by the present invention, and the increased mixing and heat treatment afforded by the matrix according to the present invention, provide for a high conversion of reactants to products. Moreover, this conversion may be obtained at lower temperatures and residence times than those required in a conventional incinerator. There is also inherent safety in the use of a process in which there are no open flames, and in which the mixture of gases to be introduced into the matrix is relatively cool, outside the flammability limits of the constituents, and therefore, not explosive under ambient conditions.
It is therefore an object of the present invention to provide a method and apparatus for flameless oxidative reaction of gases or vapors to minimize or reduce NO.sub.x emission and products of incomplete combustion.
It is yet a further object of the present invention to provide an apparatus producing a stable, yet controllably movable reaction (combustion) wave in a matrix without the use of catalytic materials.
It is a further object of the present invention to provide a method and apparatus for the destruction of gases and vapors, or the combustion of fuel, such as natural gas or organic vapors, whereby the input mixture of gases may be outside the explosion limit of the constituents. Exemplary compounds include, hydrocarbons, oxygenated hydrocarbons, aminated hydrocarbons, halogenated compounds, and sulfur-containing compounds.
It is yet another object of the present invention to provide a method and apparatus for the minimization of thermal- and fuel-NO.sub.x combustion by-products to levels substantially below those achievable by conventional combustion technologies such as premixed, nozzle-mixed, or staged burners, or by NO.sub.x removal processes such as Thermal De-NO.sub.x, Selective Catalytic Reduction, and Rap-Re-NO.sub.x. Additionally, the present invention allows for minimization or elimination of nitrous oxide (N.sub.2 O) and ammonia (NH.sub.3), which are often by-products of the NO.sub.x removal techniques.
The present process and apparatus provide a method for controlling and stabilizing the reaction or combustion of gases within a solid matrix, whereby the reactions occur without any definable flame, but rather within a reaction wave in a controlled area of the matrix, at a substantially uniform temperature.
These and other objects will be apparent from the following description, appended drawings, and from practice of the invention. The following description will be made in conjunction with reactions describing combustion, such as combustion of natural gas, but the present invention is not limited to the combustion of gases with the object of minimizing NO.sub.x and other products of incomplete combustion. The controllability and versatility of the method and apparatus according to the present invention also provide, if desired, the ability to synthesize NO, CO, hydrocarbons, or selected products of incomplete combustion, for example, by varying the outlet temperatures of the reactor, inlet composition of the stream, the residence time of the stream within the reactor, stream heating value, etc.
This method and apparatus can be functionally applied to processes where the minimization of NO.sub.x and PICs (products of incomplete combustion) is desired in conjunction with either (a) destruction of a particular gas or vapor, or (b) combustion of fuel to generate heat.